Organic light emitting devices (OLEDs) are light-emitting diodes (LEDs), which include an emissive electroluminescent layer composed of an organic compound that emits light in response to an electric current. A typical OLED has a multi-layer structure, and typically includes an indium tin oxide (ITO) anode and a metal cathode. Sandwiched between the anode and cathode are several organic layers, such as a hole injection layer (HIL), a hole transport (or transfer) layer (HTL), an emitting material layer (EML), an electron transport (or transfer) layer (ETL), an electron injection layer (EIL), and a hole blocking layer.
In order to improve the performance and lifetime of OLEDs, new electron transport layers (ETLs) and hole transport layers (HTLs) are being targeted. In the case of HTLs, the state of the art technology uses triarylamine-based materials to satisfy many of the current luminescent and phosphorescent OLED designs. Problems with current OLEDs include fast aging/short life span, undesirably high operating voltages, low efficiency and low levels of brightness. There remains a need for new HTL materials for OLED applications.